SexologyChapter 5Sex hormones, sexual differentiation, and the menstrual cycleMany of the structural differences between males and females arise before birth, during the prenatal period, in a process called prenatal sexual differentiation.Prenatal period: the time from conception to birth.Further differences develop during puberty. Hormones: chemical substances secreted by the endocrine glands into the bloodstream.Because they go into the blood, their effects are felt rapidly and at places in the body quite distant from where they were manufactured.The most important sex hormones areTestosteroneA hormone secreted by the testes in males (also present at lower levels in females)One of a group of hormones called androgens.EstrogensThe group of sex hormones secreted by the ovaries in females (and present at lower levels in males)ProgesteroneA sex hormone secreted by the ovariesThe pituitary gland and the hypothalamus are also important.The hypothalamus regulates the pituitary glandsAlso plays a part in regulating many vital behaviours.The pituitary gland regulates the other glandsIn particular the testes and ovaries.Because of this, the pituitary gland is also called master gland fo the endocrine system.Anterior lobeInteracts with the gonads (testes or ovaries)These three structures function together.They influence important sexual functionsMenstrual cyclePregnancyThe changes of pubertySexual behaviourSex hormone systems in males The pituitary and testes both produce hormones.The important hormone produced by the testes is testosterone.Has important functions in:...